Apparatus for forming self-assembled monolayers

ABSTRACT

The present application discloses forming self-assembled monolayers (SAMs) by exposing the substrate at least twice to SAM precursors with intervening cooling of a substrate.

PRIORITY APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 16/033,485, filed Jul. 12, 2018, which claims priority to U.S.Provisional Patent Application No. 62/532,515, filed Jul. 14, 2017.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

FIELD

This application relates generally to the process of preparing aself-assembled monolayer.

BACKGROUND

Atomic layer deposition (ALD) is a known process in the semiconductorindustry for forming thin films of materials on substrates, such assilicon wafers. ALD is a type of vapor deposition wherein a film isbuilt up through self-saturating surface reactions performed in cycles.In an ALD process, gaseous precursors are supplied, alternatingly andrepeatedly, to the substrate to form a thin film of material on thesubstrate. One reactant adsorbs in a self-limiting process on the wafer.A subsequent reactant pulse reacts with the adsorbed material to form amolecular layer of the desired material. The subsequent pulse can reduceor getter ligands from the adsorbed layer, can replace such ligands orotherwise add atoms (e.g., oxidize, nitridize, etc.). In a typical ALDreaction, no more than a molecular monolayer forms per cycle. Cycles canbe more complex and involve three or more reactants in sequence. Somerecognized advantages of ALD are low temperature processing and nearperfect conformality, leading to great interest in ALD for semiconductorprocessing.

Other processes besides ALD exist for forming thin films of materials onsubstrates. One such process is chemical vapor deposition (CVD), inwhich a substrate is exposed to one or more volatile precursors whichreact and/or decompose on the substrate to form a thin film. Unlike pureALD, mutually reactive reactants are often simultaneously exposed to thesubstrate in CVD. Hybrid ALD/CVD processes can allow some overlap ofprecursors to obtain some of the conformality advantages of ALD and someof the speed advantages of CVD. Both ALD and CVD can be sensitive to theexposed surface; depending upon the precursors and depositionconditions, vapor deposition processes can nucleate well or poorly ondifferent surfaces.

Invariably, during processing, deposition occurs on exposed surfacesother than those for which deposition may be desired. For example, afilm buildup can occur on exposed surfaces of a reactor as multiplesubstrates are processed in sequence. The film buildup can delaminate orflake from the reactor surfaces and contaminate the substrate surface.Large amounts of loosely adhered film buildup on the reactor surfacesalso increases the total surface area exposed to a reactant pulse,thereby increasing the pulse and purge time required to saturatesubstrate surfaces. In addition, films can be deposited on undesirableareas of semiconductor device structures, such as dielectric surfaces,entailing additional patterning and etch steps.

Currently, selective processes are available that prevent or reduce theamount of unwanted film deposition on reactor surfaces and devicestructures. Some such processes utilize a treatment process that resultsin a protective self-assembled monolayer (SAM) over reactor surfacessuch as those described in U.S. Pat. Nos. 7,914,847; 8,293,658; and9,803,277, the disclosures of which are incorporated by reference hereinin their entireties for all purposes. Other processes utilize apassivation process that deactivates some surfaces and enables aselective deposition on unpassivated substrate surfaces, such as thosedescribed in U.S. Pat. No. 8,293,658, incorporated above, and U.S.Patent Publications No. 2016-0247695 A1, 2015-0299848 A1, 2015-0217330A1, and U.S. Pat. No. 9,112,003, the disclosures of which areincorporated by reference herein in their entireties for all purposes.

Creating a SAM from the vapor phase, as opposed to a liquid phase, isadvantageous for many reasons, including the ability to use of the sameor similar type of apparatus as used in ALD and CVD. Organosilane basedSAMs may be created through vapor phase processes, but such a SAMtypically employs multiple and prolonged exposures in order to create adesired organosilane SAM.

SUMMARY

In one aspect a self-assembled monolayer (SAM) preparation process on anexposed surface of a substrate is provided. The method includessupplying a first SAM precursor to adsorb an initial SAM over an exposedsurface of the substrate. The method further includes cooling thesubstrate with the initial SAM. The method further includes supplying asecond SAM precursor to the initial SAM after the cooling to produce asupplemented SAM over the exposed surface of the substrate.

In some embodiments, the SAM preparation process further includessupplying the first SAM precursor in the vapor phase. In someembodiments, the process includes supplying the first SAM precursor at atemperature of about 80° C. to about 400° C.

In some embodiments, the first SAM precursor is a silane. In someembodiments, the silane is octadecyl(tris(dimethyl)amino)silane.

In some embodiments, the substrate is at a temperature within the rangeof about 80° C. to about 400° C. during supplying the first SAMprecursor. In some embodiments, the process further includes exposingthe exposed surface of the substrate to H₂O prior to supplying the firstSAM precursor. In some embodiments, exposing the exposed surface of thesubstrate to H₂O is performed for about 0.25 seconds to about 5 seconds.In some embodiments, supplying the first SAM precursor includessupplying for about 0.5 second to about 30 seconds. In some embodiments,the first SAM precursor is supplied at a rate of about 50 sccm to about1600 sccm in a single substrate semiconductor process chamber. In someembodiments, the process further includes soaking the exposed surface ofthe substrate for about 0.5 minute to about 15 minutes after the firstSAM precursor is supplied but before cooling the substrate.

In some embodiments, cooling includes supplying a vapor to thesubstrate, wherein the vapor is lower in temperature relative to thetemperature of the substrate. In some embodiments, the process includeswherein the vapor is ambient atmosphere. In some embodiments, theprocess includes wherein the vapor is an inert gas. In some embodiments,the process includes wherein the vapor is nitrogen gas. In someembodiments, the process includes wherein cooling includes bringing thesubstrate to about 15° C. to about 30° C. In some embodiments, coolingthe substrate is conducted for about 1 minutes to about 60 minutes. Insome embodiments, cooling the substrate is conducted for about 6 hoursto about 24 hours.

In some embodiments, the first SAM precursor is supplied in a firstdeposition chamber. In some embodiments, cooling is performed inside thefirst deposition chamber. In some embodiments, cooling is performedoutside the first deposition chamber. In some embodiments, cooling isperformed at a cooling station. In some embodiments, the process furtherincludes, after supply the second SAM precursor, placing the substrateinto a second deposition chamber different from the first depositionchamber and depositing a layer by vapor deposition selectively on anadjacent surface of the substrate relative to the supplemented SAM.

In some embodiments, the second SAM precursor is used to adsorb ontoreactive sites of the initial SAM on which the first SAM precursor isnot adsorbed to form the supplemented SAM. In some embodiments, theprocess further includes vaporizing the second SAM precursor. In someembodiments, the second SAM precursor is vaporized at a temperature ofabout 80° C. to about 400° C.

In some embodiments, the second SAM precursor is a silane. In someembodiments, the silane is octadecyl(tris(dimethyl)amino)silane. In someembodiments, the first SAM precursor and the second SAM precursor havethe same composition. In some embodiments, the first SAM precursor andthe second SAM precursor have different compositions.

In some embodiments, the process further includes re-heating thesubstrate to a temperature of about 80° C. to about 400° C. betweencooling and supplying the second SAM precursor. In some embodiments, theprocess further includes exposing the exposed surface of the substrateto H₂O after the substrate is re-heated but before the second precursoris supplied. In some embodiments, exposing the exposed surface of thesubstrate to H₂O is performed for about 0.25 seconds to about 5 seconds.

In some embodiments, the second SAM precursor is supplied in the vaporphase. In some embodiments, the second SAM precursor is supplied at atemperature of about 80° C. to about 400° C. In some embodiments, thesecond SAM precursor is vaporized at about the same temperature as thesubstrate during supplying the second SAM precursor. In someembodiments, the second SAM precursor is supplied for about 0.5 secondto about 30 seconds. In some embodiments, the second SAM precursor issupplied at a rate of about 50 sccm to about 1600 sccm in a singlesubstrate semiconductor process chamber. In some embodiments, theprocess further includes soaking the exposed surface of the substratefor about 0.5 minute to about 15 minutes after the second precursor issupplied.

In some embodiments, the initial SAM produces a water contact angle ofat most 108°. In some embodiments, the supplemented SAM produces a watercontact angle of greater than 108°. In some embodiments, thesupplemented SAM produces a water contact angle of at least 110°. Insome embodiments, the supplemented SAM produces a water contact angle ofbetween 110° to 111°. In some embodiments, the supplemented SAM ispin-hole free.

In some embodiments, the exposed surface is a surface of a reactionchamber. In some embodiments, the process further includes vapordepositing a layer on a semiconductor substrate surface within thereaction chamber selectively relative to over the supplemented SAM onthe reaction chamber surface. In some embodiments, the substrate is asurface of a patterned semiconductor substrate. In some embodiments, theprocess further includes depositing a layer on a surface of thesubstrate adjacent the supplemented SAM selectively relative to over thesupplemented SAM. In some embodiments, the exposed surface is a firstexposed surface of an insulating surface of an integrated circuitstructure. In some embodiments, the integrated circuit structurecomprises the first exposed surface and a second exposed surface. Insome embodiments, the initial SAM and supplemented SAM do not form overthe second exposed surface.

In some embodiments, the process further includes one or more additionalcycles of cooling and exposure to a third SAM precursor.

In another aspect an apparatus for depositing a self-assembled monolayer(SAM) on a surface of a substrate is provided. The apparatus includes atleast one SAM source configured for supplying at least one SAM precursorvapor. The apparatus further includes a reaction chamber configured toaccommodate a substrate on a susceptor and in fluid communication withthe at least one SAM source. The apparatus further includes a controlsystem. The apparatus further includes a control system configured todeposit an initial SAM over a surface of the substrate by communicatinga first SAM precursor vapor from the at least one SAM source. Thecontrol system is further configured to cool the substrate afterdepositing the initial SAM. The control system is further configured toform a supplemented SAM over the surface of the substrate bycommunicating a second SAM precursor vapor from the at least one SAMsource to the initial SAM after cooling the substrate.

In some embodiments, the apparatus for depositing a SAM further includesa cooling station configured to accommodate the substrate. In someembodiments, the cooling station is outside the reaction chamber,wherein the control system is configured to transfer the substrate tothe cooling station between depositing the initial SAM and forming thesupplemented SAM. In some embodiments, the apparatus further includes atransfer chamber and a load-lock chamber, and the cooling station isformed in one of the transfer chamber and the load-lock chamber.

In some embodiments, the control system is configured to cool thesubstrate to about 15° C. to about 30° C. In some embodiments, thecontrol system is configured to heat the substrate to about 80° C. toabout 400° C.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an apparatus comprising a reactionchamber according to some embodiments.

FIG. 2 is a schematic plan view of a cluster tool comprising a reactionchamber, a transfer chamber, and a load-lock chamber according to someembodiments.

FIG. 3 is a flow chart of a process for preparing a SAM on an exposedsurface of a substrate according to some embodiments.

FIG. 4 is a flow chart of a process for preparing a SAM on an exposedsurface of a substrate with cooling the substrate within a depositionchamber according to some embodiments.

FIG. 5 is a flow chart of a process for preparing a SAM on an exposedsurface of a substrate with cooling the substrate outside a depositionchamber according to some embodiments.

FIG. 6 is a flow chart of a process for preparing a SAM on an exposedsurface of a substrate including exposing a surface of a substrate toH₂O according to some embodiments.

FIG. 7 is a flow chart of a process for preparing a SAM on an exposedsurface of a substrate with heating, cooling and re-heating temperatureranges according to some embodiments.

FIG. 8 is a flow chart of a process for preparing a SAM on a firstexposed surface and subsequently selectively depositing a material byvapor deposition on a second exposed surface according to someembodiments.

DETAILED DESCRIPTION

As noted in the Background section, processes exist to deactivateparticular surfaces (e.g., reactor surfaces and surfaces of partiallyfabricated integrated circuit structures) against vapor deposition suchas ALD to allow selective deposition on untreated surfaces. One suchprocess involves forming a densely-packed, self-assembled monolayer(SAM) over exposed surfaces on which film deposition is not desired. ASAM is a relatively ordered assembly of molecules that spontaneouslyadsorb (also called chemisorb) from either vapor or liquid phaseprecursors on a surface. A typical SAM molecule includes a terminalfunctional group, a hydro-carbon chain and a head group. By forming aSAM over selected surfaces, the SAM can prevent film growth over theexposed surfaces using certain types of vapor precursors by blockingreactive sites on the exposed surface that would otherwise react withthose deposition precursors. Such selective deactivation can beparticularly effective against adsorption-driven processes, like ALD,but can also discourage certain types of CVD.

Organosilane Based SAM

The present application discloses apparatuses and processes for vaporbased deposition of organosilane based SAMs that can be formed withfewer exposures and/or take less time in order to create a desiredorganosilane SAM through the use of intermediate cooling of a substrateexposed to a SAM precursor prior to a subsequent exposure to a SAMprecursor. It is believed that intermediate cooling allows a second SAMprecursor exposure to adsorb onto reactive sites where the first SAMprecursor has not adsorbed. In some embodiments, the process ofintermediate cooling and a second SAM precursor exposure creates a SAMlayer that is dense and pin-hole free, such that it can resistnucleation even after prolonged exposure to a subsequent selectivedeposition that forms a relatively thick layer on other surfaces withoutthe SAM.

SAM precursors may include any known to a person of ordinary skill inthe art, such as thio-based and organosilane based SAM precursors. Insome embodiments, SAM precursors are identified in U.S. Pat. No.7,914,847, the disclosure of which is herein incorporated by referencein its entirety. The SAM precursor molecule may contain alkyl chainsubstituent of various carbon chain lengths. Organosilane based SAMprecursors may include, for example,octadecyl(tris(dimethyl)amino)silane, as shown below.

SAM precursors are generally of the formula R—Si-L₃, wherein the Lgroups correspond to active groups and the R group may be a carbon chainor carbon backbone. In some embodiments, the active groups may be analkylamino group (e.g., —NMe₂, —NEtMe, —NEt₂), an alkoxy group (e.g.,—OMe, —OEt), or mixtures thereof. In some embodiments, the active groupsmay be any other group which can be bound to the surface of a substrate.In some embodiments, the SAMs may contain the carbon chain length orbackbone length of 1, 2, 3, 5, 10, 15, 18, 20, 25 or 30 carbon atoms, orany range between any of these values such as, for example, 1 to 25, 2to 20 or 3 to 18 carbon atoms. In some embodiments, the carbon chain maybe an alkyl chain. In some embodiments, the carbon chain may beunsubstituted. In some embodiments, the carbon chain may be substituted.The term substituted is understood to mean that groups or atoms alongthe chain are substituted by one or more substituents. For example, asubstituted alkyl chain may have one or more of the hydrogen atoms atany position(s) along the carbon chain replaced with a substituent suchas fluorine, wherein positions along the carbon chain include theterminal ends of the carbon chain as well as positions between theterminal ends. In some embodiments, the carbon chain substituent groupsmay provide increased hydrophobicity of the SAM layer and/or anincreased water contact angle measurement. In some embodiments, thecarbon chain may be substituted by one or more fluorine groups.

Water Contact Angle

The completeness of a SAM formed over an exposed surface can becharacterized by the measured water contact angle (WCA) of the surface.In some embodiments, a SAM formed conventionally using particularprecursor(s) has a WCA of at most about 108°. In some embodiments, a SAMformed using the same precursor(s) but with intervening cooling has anincreased WCA, such as a WCA of an exposed surface is greater than 108°.In other embodiments, a SAM formed with intervening cooling has the WCAof greater than about 80°, greater than about 90°, greater than about95°, greater than about 100°, greater than about 103°, greater thanabout 106°, greater than about 108°, greater than about 109°, greaterthan about 110°, greater than about 111°, greater than about 112° orgreater than about 113°, or any range between any of these values suchas, for example, about 80° to about 113°, about 90° to about 111°, about108° to about 113° or about 110° to about 111°.

Deposition Equipment

Some embodiments of apparatuses and processes are described below forvapor based deposition of an organosilane based SAMs and selective vapordeposition.

FIG. 1 illustrates an apparatus 100 comprising a reaction chamber 102and its features after a substrate 104 has been introduced to thereaction chamber 102 according to some embodiments. The reaction chamber102 can be a CVD reaction chamber, an ALD reaction chamber, a chamberspecially designed for SAM formation, or any other type of reactionchamber capable of vapor deposition on substrate(s) such as siliconwafers. The reaction chamber 102 can be either a single-substrateprocessor or a multi-substrate processor. The substrate 104 can includean exposed surface 106, which can be patterned to include, for example,exposed insulating and conductive surfaces. The reaction chamber 102 caninclude a susceptor 108, an inlet port 110, an outlet port 112,deposition reactant source(s) 114 (which may include vaporizer(s) forlow vapor pressure reactants), a reactant source valve 116, a firstvalve 118, a passivation precursor source 120 (which may also include avaporizer), a second valve 122, a carrier gas source 124, and an outletvalve 126. The outlet valve 126 may be in fluid communication with avacuum pump 130. The various components may be electronically coupled toa controller (or set of controllers) 128. One skilled in the art willappreciate that the apparatus 100 is shown schematically only and cantake on a variety of other configurations and include other componentssuch as heaters, containers, evaporators or bubblers for various otherreactants, control systems for temperature control, control of flow forthe deposition precursors, gas distribution system, etc.

In some embodiments, the SAM precursor is vaporized in the passivationprecursor source 120. In some embodiments, the vapor source is at atemperature of about 20° C., about 40° C., about 50° C., about 70° C.,about 90° C., about 100° C., about 150° C., about 200° C., about 225°C., about 250° C., about 300° C., about 400° C., or any range betweenany of these values such as, for example, about 20° C. to about 300° C.,40° C. to about 250° C., 50° C. to about 225° C., 20° C. to about 400°C., or about 80° C. to about 400° C. In other embodiments, the vaporsource is at a temperature of about 150° C. to about 400° C. In stillother embodiments, the vapor source is at a temperature of about 200° C.to about 400° C. In yet still other embodiments, the vapor source is ata temperature of about 150° C. to about 300° C. The skilled artisan willappreciate that a suitable temperature for vaporizing without thermallydecomposing the SAM precursor will depend upon the selected precursor.In some embodiment, SAM formation may be conducted with vaporizer andsusceptor temperatures each individually set to about 20° C., about 50°C., about 100° C., about 150° C., about 185° C., about 195° C., about200° C., about 205° C., about 250° C., about 300° C., about 350° C.,about 400° C., about 195° C., or any range between any of these valuessuch as, for example, about 20° C. to about 400° C., about 50° C. toabout 300° C., about 50° C. to about 250° C., about 100° C. to about200° C., or about 185° C. to about 205° C. Experiments described belowfor SAM formation by exposure to octadecyl(tris(dimethyl)amino)silanewere conducted with both vaporizer and susceptor temperatures set tobetween 185° C. and 205° C., more particularly about 195° C.

The susceptor 108 may be used to conductively heat, cool or re-heat thesubstrate. In some embodiments, the controls are programmed to maintainthe susceptor 108 at a temperature suitable for adsorption of the SAM ofinterest, which may be similar to the ranges noted above for precursorvaporization. In some embodiments the controls may also be programmed tocool the susceptor 108 in accordance with the sequences described below.

While illustrated with a substrate 104 on the susceptor 108, it will beunderstood in view of the disclosure below that, in some embodiments,the substrate on which the passivation layer is formed may be the wallsof the reaction chamber 102 itself, such that the substrate 104 on whichsubsequent deposition on unpassivated surfaces is desired may be absentfrom the chamber 102 during the formation of the passivation layer.

While FIG. 1 shows separate reactant source(s) 114, in some embodimentsthe apparatus 100 is a dedicated SAM exposure reactor, such that thereaction chamber 102 is not connected to vapor sources other than theSAM precursor molecules in the passivation precursor source 120 andinert gas, such as N₂, He or Ar in the carrier gas source 124.

FIG. 2 is a schematic plan view of a cluster tool 200 comprising a firstprocess chamber 202 a, a second process chamber 202 b, a transferchamber 204, and a load-lock chamber 206 according to some embodiments.The chambers have gate valves 210 between them, and the transfer chamber204 may include a transfer robot. In some embodiments, the transferchamber 204 may comprise a cooling station 208. One skilled in the artwill appreciate that the cluster tool 200 is shown schematically onlyand can take on a variety of other configurations and include additionalor other components such as additional process chamber(s) 202, heaters,evaporators or bubblers, control systems for temperature control,control of flow for the deposition precursors, gas distribution system,etc.

In some embodiments, the cluster tool may comprise multiple reactionchambers, transfer chambers, and load-lock chambers. In someembodiments, the cluster tool environment may not comprise a transferchamber. In some embodiments, cooling as described below may beperformed in the reaction chamber. In other embodiments, cooling may beperformed in the transfer chamber at the cooling station. In still otherembodiments, cooling may be performed in the load-lock chamber. In stillother embodiments, cooling may be performed outside the cluster tool. Inyet still other embodiments, cooling may be performed in any otherdedicated cooling chamber or station in the cluster tool environment. Insome embodiments, cooling may be actively performed, such asconvectively using air or inert gas (such as nitrogen, helium, argon, ormixtures thereof), or conductively by moving colder elements intoproximity or contact with the substrate or susceptor. In embodimentsemploying convective cooling stations, the cooling station may beplumbed only with inert gases, without connection to reactive gases. Insome embodiments, cooling may be conducted passively by removing thesubstrate from a heat source but without active cooling. In someembodiments, substrates may be stored in the cooling chamber or stationbefore deposition of the SAM on the substrates. In some embodiments, thecooling chamber or station may be configured to hold one substrate ormay be configured to hold more than one substrate. In some embodiments,the cooling chamber or station may be configured to hold 1 or moresubstrates, 2 or more substrates, 3 or more substrates, 5 or moresubstrates, 10 or more substrates, 15 or more substrates or 25 or moresubstrates, or any range between any of these values.

Process Flow

FIG. 3 is a flow chart of a process for preparing a SAM on a surface ofa substrate according to some embodiments. The process comprisessupplying 310 a first SAM precursor to an exposed surface of asubstrate; thereby adsorbing 320 an initial SAM on the exposed surfaceof the substrate; cooling 330 the substrate after adsorbing 320 theinitial SAM; supplying 340 a second SAM precursor to the exposed surfaceof the substrate after cooling 330; thereby producing 350 a supplementedSAM on the exposed surface of the substrate.

In some embodiments, supplying a first SAM precursor may comprise a SAMprecursor exposure pulse of about 0.1 second to about 30 minutes. Inother embodiments, supplying a first SAM precursor may comprise a SAMprecursor exposure pulse of about 0.5 seconds to about 30 seconds. Instill other embodiments, supplying a first SAM precursor may comprise aSAM precursor exposure pulse of about 1 second to about 10 seconds. Insome embodiments, supplying a first SAM precursor may additionallycomprise a SAM precursor soak of about 10 seconds to about 30 minutes,wherein an exposure soak comprises continued exposure of the substrateto the SAM precursor, and may include sealing the outlets of the processchamber to trap the SAM precursor in the process chamber. In otherembodiments, supplying a first SAM precursor may additionally comprise aSAM precursor soak of about 0.5 minute to about 15 minutes. In stillother embodiments, supplying a first SAM precursor may comprise a SAMprecursor exposure soak of about 1 minute to about 10 minutes. The flowrate will depend on SAM formation condition and the size of the chamber.For a single-substrate process chamber for a 300-mm wafer, for example,supplying a first SAM precursor may comprise a SAM precursor flow rateof about 50 sccm to about 1600 sccm. In experiments described below,supplying the first SAM precursor comprised a SAM precursor flow rate ofabout 800 sccm for about 5 seconds followed by a 5 min. soak.

In some embodiments, cooling may be performed convectively using air orambient atmosphere. In other embodiments, cooling may be performedconvectively using an inert gas, for example nitrogen gas. In stillother embodiments, cooling may be performed conductively by activelycooling the susceptor 108 or other support for the substrate 104. Instill other embodiments, cooling may be performed passively by removingthe substrate from the heat source used during passivation precursorexposure, and may involve placing the substrate on a station or merelyholding the substrate with a transfer robot until sufficiently cooled.In some embodiments, cooling may be performed for about 1 second, about5 seconds, about 10 seconds, about 60 seconds, about 300 seconds, about600 seconds, about 1 minute, about 1 minute, about 5 minute, about 5minute, about 15 minute, about 30 minute, about 60 minute or about 24hours, or any range between any of these values such as, for example,about 1 second to about 600 seconds, about 5 seconds to about 300seconds, about 10 seconds to about 60 seconds, about 1 minute to about30 minutes or about 1 minute to about 15 minutes. In some embodiments,cooling may be performed for less than 10 seconds, less than 30 seconds,less than 60 seconds, less than 5 minutes, less than 10 minutes, lessthan 15 minutes, less than 30 minutes or less than 60 minutes. In someembodiments, cooling may be performed for about 1 minute to about 60minutes. In some embodiments, cooling may be performed for about 6 hoursto about 24 hours. Blast cooling or quick cooling may refer to coolingtimes of about 60 seconds or less. Normal cooling may refer to coolingtimes of about 60 seconds or more, such as about 1 minute to about 30minutes.

In some embodiments, cooling is performed to less than or at about 100°C., less than or at about 75° C., less than or at about 50° C., lessthan or at about 30° C., less than or at about 25° C., less than or atabout 20° C., less than or at about 15° C. In some embodiments, coolingis performed to about 0° C. to about 50° C. In some embodiments, coolingis performed to about 15° C. to about 30° C. In still other embodiments,cooling is performed to about 20° C. to about 25° C. In yet still otherembodiments, cooling is performed to about 20° C. or room temperature.In some embodiments employing active or blast cooling, the final coolingtemperature may be below freezing at about 0° C. or less, at about −10°C. or less, at about −25° C. or less, at about −50° C. or less, at about−80° C. or less, at about −100° C. or less, or at about −200° C. orless, or any range between any of these values. In some embodiments,cooling is performed to a final temperature that is below the SAMformation temperature. In some embodiments, cooling is performed to atemperature below the SAM formation temperature by about 50° C. or more,by about 100° C. or more, by about 125° C. or more, by about 150° C. ormore or vy about 175° C. or more, or any range between any of thesevalues. In some embodiments, cooling is performed to about 75% less thanthe SAM formation temperature (as measured in Celsius), about 50% lessthan the SAM formation temperature, about 35% less than the SAMformation temperature, about 20% less than the SAM formationtemperature, about 15% less than or about 10% less than the SAMformation temperature, or any range between any of these values.

In some embodiments, cooling to a desired temperature may be performedin one step. In some embodiments, cooling to a desired temperature maybe performed in more than one steps, wherein a substrate may be cooledto one or more intermediate temperatures and then subsequently cooled toa final desired temperature. In some embodiments, the one or moreintermediate cooling steps may perform the cooling an intermediatetemperature that is below the SAM formation temperature. In someembodiments, the intermediate cooling temperatures are below the SAMformation temperature by about 20° C. or more, by about 50° C. or more,by about 75° C. or more or by about 100° C. or more, or any rangebetween any of these values. In some embodiments, the intermediatecooling temperatures are about 15% less than the SAM formationtemperature (as measured in Celsius), about 25% less than the SAMformation temperature, about 30% less than the SAM formationtemperature, about 40% less than the SAM formation temperature, about50% less than the SAM formation temperature, about 60% less than the SAMformation temperature, about 70% less than the SAM formationtemperature, about 80% less than the SAM formation temperature, about90% less than the SAM formation temperature, or any range between any ofthese values such as, for example, 15% to 90%, 25% to 70% or 30% to 60%.

In some embodiments, supplying a second SAM precursor may compriseexposing the substrate to a SAM precursor for about 0.1 second to about30 minutes. In other embodiments, supplying a second SAM precursor maycomprise exposing the substrate to a SAM precursor for about 0.5 secondto about 20 seconds. In still other embodiments, supplying a second SAMprecursor may comprise a SAM precursor exposure of about 1 second toabout 10 seconds. In some embodiments, supplying a second SAM precursormay additionally comprise a SAM precursor soak of about 10 seconds toabout 30 minutes, wherein a soak comprises continued exposure of thesubstrate to the SAM precursor, and may include sealing the outlets ofthe process chamber to trap the SAM precursor in the process chamber. Inother embodiments, supplying a second SAM precursor may comprise a SAMprecursor soak of about 0.5 minute to about 15 minutes. In still otherembodiments, supplying a second SAM precursor may comprise a SAMprecursor soak of about 1 minute to about 10 minutes. The flow rate willdepend on SAM formation condition and the size of the chamber. For asingle-substrate process chamber for a 300-mm wafer, for example,supplying a second SAM precursor may comprise a SAM precursor flow rateof about 50 sccm to about 1600 sccm. In experiments described below,supplying the second SAM precursor comprised a SAM precursor flow rateof about 800 sccm for about 5 seconds followed by a 5 min. soak.

In some embodiments, the process for preparing a SAM on a surface of asubstrate comprises one or more additional cycles of cooling andexposure to a third SAM precursor. In some embodiments, an additionalcycle of cooling and exposure to a third SAM precursor may be performedsubsequent to cooling 330 and prior to supplying 340 a second SAMprecursor. In some embodiments, an additional cycle of cooling andexposure to a third SAM precursor may be performed subsequent tosupplying 340 a second SAM precursor. In some embodiments, the third SAMprecursor may comprise the first SAM precursor, the second SAMprecursor, a SAM precursor different from the first or second SAMprecursor, or mixtures thereof.

It will be understood by a person of ordinary skill in the art that thefirst and second SAM precursor exposures may be performed independentlyat any vapor source temperature described throughout the specification.It will be understood by a person of ordinary skill in the art that thefirst and second SAM precursors may have the same compositions. Inexperiments described below, both the first and second SAM precursorscomprise octadecyl(tris(dimethyl)amino)silane. The first and secondprecursor exposures can be performed in different process chambers butwill more often be conducted in the same process chamber, particularlywhen employing the same precursor for both exposures. The processchamber may be the same or different from one employed for a subsequentselective ALD process.

It will also be understood by a person of ordinary skill in the art thatthe first and second SAM precursors may have different compositions. Inone embodiment, the first SAM precursor may be a long-chain moleculewhile the second SAM precursor may be a short-chain molecule. In anotherembodiment, the first SAM precursor may be a short-chain molecule whilethe second SAM precursor may be a long-chain molecule. In someembodiments, the number of carbon atoms is greater than or equal toeight for long-chain molecules, while less than eight for short-chainmolecules. In other embodiments, the number of carbon atoms is greaterthan or equal to twelve for long-chain molecules. In other embodiments,the number of carbon atoms is less than or equal to six for short-chainmolecules. SAM precursors with different compositions are disclosed inU.S. Pat. Nos. 7,914,847 and 8,293,658, the entire disclosures of whichare incorporated herein by references for all purposes.

FIG. 4 is a flow chart of a process for preparing a SAM on an exposedsurface of a substrate including intervening cooling of the substratewithin a deposition chamber according to some embodiments. The processcomprises supplying 410 a first SAM precursor to an exposed surface of asubstrate in a deposition chamber; thereby adsorbing 420 an initial SAMon the exposed surface of the substrate; subsequently cooling 430 thesubstrate within the deposition chamber; subsequently supplying 440 asecond SAM precursor to the exposed surface of the substrate; therebyproducing 450 a supplemented SAM on the exposed surface of thesubstrate. The process described in FIG. 4 is similar to the processdescribed with respect to FIG. 3 except that cooling of the substrate isspecified to be performed within the deposition chamber. Methods ofcooling the substrate within the deposition chamber may be as describedabove (e.g., convectively cooling by supply of cool air or inert gas,active conductive cooling of the susceptor in the process chamber,etc.).

FIG. 5 is a flow chart of a process for preparing a SAM on an exposedsurface of a substrate with cooling the substrate outside a depositionchamber according to some embodiments. The process comprises supplying510 a first SAM precursor to an exposed surface of a substrate in adeposition chamber; thereby adsorbing 520 an initial SAM on the exposedsurface of the substrate; removing 530 the substrate from the depositionchamber; cooling 540 the substrate; placing 550 the substrate into adeposition chamber; supplying 560 a second SAM precursor to the exposedsurface of the substrate; thereby producing 570 a supplemented SAM onthe exposed surface of the substrate. In some embodiments, the first andsecond precursors are the same type of precursor. In some embodiments,both precursors are supplied in the same deposition chamber. The processdescribed in FIG. 5 is similar to the process described with respect toFIG. 3 except that cooling of the substrate is specified to be performedoutside the deposition chamber. Methods of cooling the substrate outsidethe deposition chamber may be similar to those described above (e.g.,passive cooling, convective cooling, conductive cooling by contact orclose proximity with an actively cooled element), and may be conductedin a load-lock chamber, a transfer chamber, or another process chamber.

FIG. 6 is a flow chart of a process for preparing a SAM on an exposedsurface of a substrate including exposing a surface of a substrate toH₂O according to some embodiments. The process comprises exposing 610 asurface of a substrate to H₂O; subsequently supplying 620 a first SAMprecursor to the exposed surface of the substrate; thereby adsorbing 630an initial SAM on the exposed surface of the substrate; subsequentlycooling 640 the substrate; exposing 650 the surface of the substrate toH₂O; subsequently supplying 660 a second SAM precursor to the exposedsurface of the substrate; thereby producing 670 a supplemented SAM onthe exposed surface of the substrate. The process described in FIG. 6 issimilar to the process described with respect to FIG. 3 except that thesurface of the substrate is exposed to H₂O before each supply of SAMprecursor. It should be understood that the term “exposed surface”describes the same surface of a substrate as described in FIGS. 3-5 evenif the surface is treated with H₂O or any other intervening treatments.In some embodiments, the surface of the substrate is exposed to H₂Obefore supplying the first SAM precursor, but the surface of thesubstrate is not exposed to H₂O before supplying the second SAMprecursor. In other embodiments, the surface of the substrate is exposedto H₂O before supplying the second SAM precursor, but the surface of thesubstrate is not exposed to H₂O before supplying the first SAM monolayerprecursor. As noted above, the first and second SAM precursors can havethe same composition. Cooling can be conducted within the depositionchamber or outside (e.g., within the load-lock chamber, in the transferchamber or in another process chamber). In some embodiments, the surfaceof the substrate is exposed to H₂O for about 0.1 seconds to about 10seconds. In other embodiments, the surface of the substrate is exposedto H₂O for about 0.25 seconds to about 5 seconds. In experimentsdescribed below, the surface of the substrate is exposed to H₂O forabout 1 second.

FIG. 7 is a flow chart of a process for preparing a SAM on an exposedsurface of a substrate. The process comprises supplying and heating 710a substrate to a temperature suitable for SAM formation; supplying 720 afirst SAM precursor to an exposed surface of the substrate; therebyadsorbing 730 an initial SAM on the exposed surface of the substrate;subsequently cooling 740 the substrate to facilitate subsequent SAMsupplementation; re-heating 750 the substrate; subsequently supplying760 a second SAM precursor to the exposed surface of the substrate;thereby producing 770 a supplemented SAM on the exposed surface of thesubstrate. The process described in FIG. 7 is similar to the processdescribed with respect to FIG. 3 except that heating and re-heating ofthe substrate, before and after cooling, are specified. As noted above,the first and second SAM precursors can have the same composition. Thetemperature ranges for each stage can be as noted above. In someembodiments, the substrate is heated using a susceptor in the processchamber. The susceptor and substrate can be heated radiantly,resistively or inductively. Methods of cooling the substrate may asdescribed above, that is, within the deposition chamber or outside(e.g., within the load-lock chamber, in the transfer chamber or inanother process chamber).

Deposition

In some embodiments, following SAM formation as described above,material(s), such as metallic materials (e.g., elemental metal, metaloxide, metal nitride, metal alloys, etc.), is/are selectively depositedon a second surface relative to a first surface by a vapor depositionprocess, where the first surface comprises a SAM formed by processesdescribed herein. In some embodiments, the first surface is aninsulating surface. In other embodiment, the first surface is aconductive surface. In some embodiments, the first surface is a surfaceof an integrated circuit structure, such as on a semiconductorsubstrate. In some embodiments the reactants include a first hydrophobicreactant and a second reactant. The first hydrophobic reactant andsecond reactant can be selected to deposit the desired material.Additional reactants (third reactant, fourth reactant etc . . . ) can beutilized in some embodiments, for example to contribute additionalcomponents to the material that is deposited. In some embodiments thesecond surface is substantially reactive to one or more of the vaporphase reactants, while the first surface is not substantially reactive.

In some embodiments the vapor deposition process is an ALD-type processin which at least one reactant adsorbs largely intact in a self-limitingprocess. In some embodiments the deposition process may be a vapordeposition process in which at least one of the reactants is at leastpartially decomposed, such as selectively decomposed on the firstsurface. For example, in some embodiments the vapor deposition processmay be a chemical vapor deposition (CVD) process, such as a sequentialor cyclic CVD process or a single source CVD process.

FIG. 8 is a flow chart of a process for preparing a SAM on a firstexposed surface and subsequently selectively depositing a material byvapor deposition on a second exposed surface. The process comprisessupplying 810 a first SAM precursor to a first exposed surface; therebyadsorbing 820 an initial SAM on the first exposed surface; subsequentlycooling 830 the substrate; subsequently supplying 840 a second SAMprecursor to the first exposed surface; thereby producing 850 asupplemented SAM on the first exposed surface; and subsequentlyselectively depositing 860 by vapor deposition a material on a secondexposed surface relative to the deposition on the first exposed surfacewith its supplemented SAM thereon. The process described in FIG. 8 issimilar to the process described with respect to FIG. 3 except forspecifying that a material is subsequently selectively deposited on asecond surface relative to the deposition on the first exposed surface.Methods of selective deposition on a variety of exposed surfaces may besimilar to those described above. The selective deposition 860 may beconducted in the same or a different deposition chamber from thechamber(s) in which SAM is supplied 810/840. For example, with referenceto FIG. 2, SAM formation using first and second SAM exposures may takeplace in the first process chamber 202 a while selective deposition isperformed in the second process chamber 202 b. In another example,initial SAM formation using a first SAM exposure may take place in thefirst process chamber 202 a while supplemented SAM formation using asecond SAM exposure may take place in the second process chamber 202 b,and selective deposition is performed in a third process chamber.

Selectivity

The SAM formation described herein may be selective. For example, theSAM may naturally adsorb on some types of surfaces and not adsorb onother, chemically or morphologically different surfaces. Furthermore,the subsequent deposition may be selective, as described above withrespect to selective deposition 860 in FIG. 8.

In some embodiments, a material is selectively deposited on a secondsubstrate surface relative to a different, first surface. Selectivitycan be given as a percentage calculated by [(deposition on secondsurface)−(deposition on first surface)]/(deposition on the secondsurface). Deposition can be measured in any of a variety of ways. Insome embodiments, deposition may be given as the measured thickness ofthe deposited material. In some embodiments, deposition may be given asthe measured amount of material deposited.

In some embodiments, selectivity is greater than about 10%, greater thanabout 50%, greater than about 75%, greater than about 85%, greater thanabout 90%, greater than about 93%, greater than about 95%, greater thanabout 98%, greater than about 99% or even greater than about 99.5%. Inembodiments described herein, the selectivity can change over theduration or thickness of a deposition.

In some embodiments deposition on the second surface of the substraterelative to the first surface of the substrate is at least about 80%selective, which may be selective enough for some particularapplications. In some embodiments the deposition on the second surfaceof the substrate relative to the second surface of the substrate is atleast about 50% selective, which may be selective enough for someparticular applications. In some embodiments the deposition on thesecond surface of the substrate relative to the first surface of thesubstrate is at least about 10% selective, which may be selective enoughfor some particular applications. As is known in the art, partiallyselective deposition can be followed by a short etch, which may removeall of the deposited material from the unfavored first surface, whileleaving some of the deposited material on the favored second surface.

In some embodiments, deposition occurs favorably on the second surface,such as a metallic surface, a metallic surface comprising oxygen or adielectric surface, and is not favored on the first surface, such as anorganic surface (e.g., the SAM described herein). In some embodiments,the first and second surfaces may be surfaces of the same substrate(e.g., surfaces of the same wafer or process chamber). In otherembodiments, the first and second surfaces may be surfaces of thedifferent substrates (e.g., the surface of a wafer and the surface of aprocess chamber, or vice versa).

Experiments

Examples 1-10 were performed using Octadecyl(tris(dimethyl)amino)silaneCH₃(CH₂)₁₇Si(N(CH₃)₂)₃ as a SAM precursor both before and after cooling.“1 cycle” means 5 seconds of a SAM precursor pulse followed by a 5minute soak. “1 cycle with H₂O” means 1 second of an H₂O pulse followedby 5 seconds of a SAM precursor pulse followed by a 5 minute soak. TheSAM was prepared with a substrate temperature of 195° C., a vapor sourcetemperature of 195° C., and a precursor flow rate of 800 sccm. The watercontact angles (WCA) of the resulting SAMs were measured.

TABLE 1 SAM Step 1 Step 2 Step 3 WCA [°] Example 1 1 cycle Max 107°Example 2 2-4 cycle Max 108° Example 3 1-4 cycles Max 108° with H2Opulse Example 4 1 cycle Air break 30 1 cycle 111° min or more Example 5H2O Air break 30 H2O 111° pulse 1 s + min or more pulse 1 s + 1 cycle 1cycle Example 6 1 cycle Load lock 30 1 cycle Max 107° min Example 7 H2OLoad lock 30 H2O Max 107° pulse 1 s + min pulse 1 s + 1 cycle 1 cycleExample 8 H2O Load lock H2O 110° pulse 1 s + over night pulse 1 s + 1cycle 1 cycle Example 9 1 cycle 30 min wait 1 cycle Max 107° in areactor Example 10 1 cycles 60 min wait 1 cycle Max 107° in reactor

As it can be seen, the number of cycles of SAM precursor and the supplyor non-supply of H₂O have little effect on the WCA if there is nocooling. On the other hand, cooling can have a significant effect onWCA. In the chart above, “air break” represents a cooling step becausethe substrate was removed from the hot susceptor to an environment whereit could readily cool. Removing the substrate to a load lock for 30minutes may not have resulted in significant cooling due to the lowpressures maintained in the load lock slowing the rate of cooling,whereas leaving the substrate in the load lock overnight cooled thesubstrate sufficiently to result in a high WCA.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope or spirit of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided that they come within the scope ofthe appended claims or their equivalents.

What is claimed is:
 1. An apparatus for depositing a self-assembledmonolayer (SAM) on a surface of a substrate, comprising: at least oneSAM source configured for supplying at least one SAM precursor vapor; areaction chamber configured to accommodate a substrate on a susceptorand in fluid communication with the at least one SAM source; and acontrol system configured to cause the apparatus to: deposit an initialSAM over a surface of the substrate by communicating a first SAMprecursor vapor from the at least one SAM source; cool the substrateafter depositing the initial SAM; and form a supplemented SAM over theinitial SAM on the surface of the substrate by communicating a secondSAM precursor vapor from the at least one SAM source to the initial SAMafter cooling the substrate.
 2. The apparatus of claim 1, furthercomprising a cooling station configured to accommodate the substrate,wherein the control system is configured to cause the apparatus totransfer the substrate to the cooling station between depositing theinitial SAM and forming the supplemented SAM.
 3. The apparatus of claim2, wherein the cooling station is outside the reaction chamber.
 4. Theapparatus of claim 2, wherein the apparatus further comprises a transferchamber and a load-lock chamber, and the cooling station is in thetransfer chamber.
 5. The apparatus of claim 2, wherein the apparatusfurther comprises a transfer chamber and a load-lock chamber, and thecooling station is the load-lock chamber.
 6. The apparatus of claim 1,wherein the control system is configured to cause the apparatus to coolthe substrate in the reaction chamber after depositing the initial SAM.7. The apparatus of claim 1, wherein the control system is configured tocause the apparatus to cool the susceptor to thereby cool the substrateafter depositing the initial SAM.
 8. The apparatus of claim 1, whereinthe control system is configured to cause an element colder than thesubstrate to move into proximity with the substrate to thereby cool thesubstrate after depositing the initial SAM.
 9. The apparatus of claim 1,wherein the control system is configured to cause an element colder thanthe substrate to move into contact with the substrate or the susceptorto thereby cool the substrate after depositing the initial SAM.
 10. Theapparatus of claim 1, wherein the control system is configured to causethe apparatus to cool the substrate to a temperature in a range fromabout 15° C. to about 30° C.
 11. The apparatus of claim 1, wherein thecontrol system is configured to cause the apparatus to heat thesubstrate to a temperature in a range from about 80° C. to about 400° C.12. The apparatus of claim 1, wherein the control system is configuredto cause the apparatus to cool the substrate after depositing theinitial SAM while supplying an inert gas to the substrate.
 13. Theapparatus of claim 1, wherein the control system is configured to causethe apparatus to cool the substrate after depositing the initial SAMwhile supplying a vapor to the substrate, wherein the vapor is lower intemperature relative to a substrate temperature thereby convectivelycooling the substrate.
 14. The apparatus of claim 1, wherein the controlsystem is configured to cause the apparatus to cool the substrate afterdepositing the initial SAM by reducing a temperature of the substrate byat least about 50° C. relative to a substrate temperature duringdepositing the initial SAM.
 15. The apparatus of claim 1, wherein thecontrol system is configured to cause the apparatus to cool thesubstrate to a temperature of 0° C. or less.
 16. The apparatus of claim1, wherein the control system is configured to cause the apparatus tocool the substrate to a temperature in a range from about 0° C. to about−200° C.
 17. The apparatus of claim 1, wherein the control system isfurther configured to cause the apparatus to selectively vapor deposit alayer on a substrate surface within the reaction chamber relative toover the supplemented SAM.
 18. The apparatus of claim 1, furthercomprising a second reaction chamber, wherein the control system isfurther configured to cause the apparatus to: place the substrate in thesecond reaction chamber after the supplemented SAM is formed; and in thesecond reaction chamber, deposit a layer by vapor deposition selectivelyon an adjacent surface of the substrate relative to the supplementedSAM.
 19. The apparatus of claim 1, wherein the control system is furtherconfigured to cause the apparatus to expose the surface of the substrateto H2O after the substrate is re heated following cooling and before thesupplemented SAM is formed.
 20. An apparatus for depositing aself-assembled monolayer (SAM) on a surface of a substrate, comprising:at least one SAM source configured for supplying at least one SAMprecursor vapor; a reaction chamber configured to accommodate asubstrate on a susceptor and in fluid communication with the at leastone SAM source; and a control system configured to cause the apparatusto: deposit an initial SAM over a surface of the substrate bycommunicating a first SAM precursor vapor from the at least one SAMsource; cool the substrate after depositing the initial SAM for a timein a range from about 1 minute to about 60 minutes; and form asupplemented SAM over the initial SAM on the surface of the substrate bycommunicating a second SAM precursor vapor from the at least one SAMsource to the initial SAM after cooling the substrate.